1. Field of the Invention
The present invention relates to a head stack assembly (hereafter referred to as xe2x80x9cHSAxe2x80x9d), that supports a magnetic head which accesses a magnetic disk within a magnetic storage device for computers such as a hard disk drive.
2. Description of the Related Art
Recent rapid progress of miniaturizing personal computers requires rapid development of more miniaturized hard disk drives, etc. which is used as magnetic storage devices for computers. As the processing speed of personal computers is being made higher and higher ever, the required storage capacity of the magnetic storage devices is being increased day by day.
To promote the miniaturization of the hard disk drive, the magnetic disk per se is being decreased in diameter remarkably. In fact, the diameter of the magnetic disk has been changed from 5 inches through 3.5 inches, 2.5 inches, 1.8 inches to 1 inch. The decrease in disk diameter, however, makes it more difficult to increase the storage capacity per one magnetic disk, and accordingly, there arises a need of using a plurality of magnetic disks.
FIG. 4 schematically shows an internal structure of a hard disk drive. A plurality of magnetic disks D are arranged with constant clearances on and along a rotational axis C1, and rotationally driven integrally by a spindle motor not illustrated. Data read/write of the magnetic disks D are carried out by a head stack assembly (HSA) 1. The HSA 1 is provided with a plurality of head suspensions 2 having leading end portions supporting magnetic heads (not shown) thereon. An actuator block 3 is formed by multi-staged suspension supporting portions 3a for supporting the respective head suspensions 2, and rotatably supported by a pivot assembly 4.
The pivot assembly 4 is arranged on a rotational axis C2 parallel to the rotational axis C1, and a shaft 5 is passed through a central portion thereof. The pivot assembly 4 further includes a sleeve 6 supported through a bearing onto the shaft 5. Since the actuator block 3 is fixed with respect to the sleeve 6, the respective head suspensions 2 are made integrally pivotable about the rotational axis C2.
Although not illustrated, a coil is provided in an end portion 3b located opposite from the head suspensions 2 with respect to the rotational axis C2, and magnets are disposed in such a manner that the coil is interposed between the magnets to form a so-called voice coil motor. With the excitation of the voice coil motor, the HSA 1 is pivoted or swung about the rotational axis C2 to move the magnetic head to a desired position on the magnetic disk D.
Since the hard disk drive faces the contradictory demands, i.e. the decreased size and the increased storage capacity as discussed above, the hard disk drive is required to have a multi-staged arrangement of the magnetic disks D. That is, three to ten magnetic disks D are stacked as required, and the suspension supporting portions 3a of the actuator block 3 are multi-staged more correspondingly to support a larger number of the head suspensions 2 (and the magnetic heads).
The multi-stage arrangement of the magnetic disks D however causes the following new problem. That is, although the storage capacity can be increased in association with the multi-stage arrangement of the magnetic disks D, the data read/write speed, which is one of the requirements for the hard disk drive, can not be increased correspondingly to the increased storage capacity. This is because the head suspensions 2 are all pivoted integrally, and thus the magnetic heads supported by the respective head suspensions 2 are all moved integrally on the disks D, that is, the reading/writing cannot be performed to each of the plurality of magnetic disks in parallel or concurrently.
The present invention has been made in order to solve the above-mentioned problem, and an object thereof is to realize a magnetic storage device for computers such as a hard disk drive, to meet all the requirements, i.e. miniaturization in size, the increased capacity, and the increased data reading/writing speed, thereby enhancing more performance of the magnetic storage device for computers.
To achieve the above-noted object, a head stack assembly according to a first aspect of the present invention is arranged to have a pivot assembly provided with a plurality of pivots that support a plurality of actuator blocks supporting head suspensions so as to be independently rotatable while being arranged such that rotational axes thereof are made in series.
With this arrangement, the plurality of actuator blocks supporting the head suspensions are rotated one by one using the plurality of pivots, making it possible to independently control a position of the magnetic heads for access to different magnetic disks.
The head stack assembly according to a second aspect of the present invention is arranged such that the plurality of pivots are rotatably supported to a common shaft. Therefore, the shaft, the plurality of pivot assemblies pivotally-supported to the shaft, the actuator blocks pivotally-supported to the respective pivot assemblies, and the suspension heads supported to the respective actuator blocks can be formed as a module.
The head stack assembly according to a third aspect of the present invention is arranged such that the sleeves are supported through bearings to the shaft, and a spacer is disposed between two adjacent sleeves. With this arrangement, a setting clearance between the actuator blocks fixed to the respective sleeves is held properly, and a desired pre-load is applied to the bearings located inside the pivot assembly.
To achieve the above-noted object, a supporting method of a head stack assembly according to a fourth aspect of the present invention is arranged such that a plurality of actuator blocks supporting head suspensions are supported so as to be independently rotatable, while being arranged such that rotational axes thereof are made in series. With this arrangement, position of the magnetic heads to be accessed to different magnetic disks is controlled independently by the actuator-block-basis.